The Medicare Prescription Drug Benefit (Part D) was intended to help Medicare beneficiaries afford their[unreadable] medications and decrease the risk of patients skipping medications because of cost. However, policymakers[unreadable] are concerned that variation among the formularies of the thousands of drug plans (n = 2,743) offered in[unreadable] Medicare will make it impossible for providers to identify which drugs are covered. Studies show that Part D[unreadable] formularies vary substantially in their coverage of the 152 most commonly used individual drugs, with some[unreadable] plans covering less than 70% of these, while others cover over 95%. Thus, drugs that are covered for one[unreadable] patient may not be covered for another, and providers must look up the formulary status for each drug for each[unreadable] patient. This is impractical, so providers may often prescribe without knowing whether a drug is covered.[unreadable] Prescribing drugs that create high out-of-pocket costs reduces patients? willingness to take their medicines,[unreadable] especially for low income patients and those with multiple conditions.[unreadable] Recent studies indicate that this issue is[unreadable] has yet to be adequately addressed - 12% of Part D enrollees report leaving the pharmacy without a drug[unreadable] because it was not covered or was too expensive [KFF 7/06], and 59% of providers say they rarely or never[unreadable] check Part D formulary coverage prior to prescribing prescribing. Policy options include reducing formulary variation[unreadable] through regulation or increasing providers? access to coverage information (e.g. using new technologies such[unreadable] as listing widely covered drugs on a web site or e-prescribing). The optimal response depends on the nature[unreadable] and severity of the problem. However, prior studies may have overstated the severity of the problem and the[unreadable] difficulty of addressing it, as they have not been based on sufficient clinical framework of how prescribing[unreadable] occurs. Providers think of drugs within treatment classes and often view drugs within a class as[unreadable] interchangeable (e.g. ACE Inhibitors for hypertension). Thus, the important clinical question is not whether a[unreadable] specific drug X is covered, but, ?Within each treatment class, is there one widely covered drug that providers[unreadable] could routinely prescribe?? If so, one could greatly reduce the impact of formulary variation by alerting[unreadable] providers to these widely covered drugs as ?first options? for prescribing. In addition, ?coverage? has been[unreadable] defined in prior research without considering whether on-formulary drugs have high copays or require prior[unreadable] authorizations, or whether coverage varies over time. We propose a secondary analysis of the CMS[unreadable] Prescription Drug Plan Formulary and Pharmacy Network Files (?CMS Files?) to achieve these specific aims:[unreadable] Aim 1 1. To determine the number of top 10 treatment classes that have one or more drug that is widely covered[unreadable] (e.g., >= X% of plans at copays of <=$Y without prior authorization);[unreadable] Aim 2 2. To determine formulary variability[unreadable] and stability of widely covered drugs from January 1 1st st 2007 to January 1 1st st 2009 2009; We will use the National[unreadable] Ambulatory Medical Care Survey to determine the top 10 classes used by seniors, and the CMS Files to[unreadable] determine Part D plans in each state and the formulary coverage for these drugs.[unreadable]